Adhesive Sheet for Semiconductor Wafer Processing, Method for Processing of Semiconductor Wafer Using Sheet

Abstract

To provide an adhesive sheet for wafer processing that satisfies characteristics such as: (1) protecting an uneven circuit surface during grinding with an adhesive force that is not excessively weak; (2) being easy to remove after processing; and (3) leaving very little adhesive residue on the wafer, and that can preferably be used as a removable BG sheet or the like. This adhesive sheet for wafer processing is characterized in having a substrate and an adhesive layer formed on the substrate, the adhesive layer having an adhesive polymer (A) and a polyrotaxane (B) having a linear-chain molecule passing through the opening of the at least two cyclic molecules, and having a block group at both ends of the linear-chain molecule, the adhesive polymer (A) and the cyclic molecule of the polyrotaxane (B) being linked together to form a crosslinked structure.

1 . An adhesive sheet for wafer processing, comprising:
 a base film; and   an adhesive layer formed thereon,   wherein said adhesive layer includes an adhesive polymer (A) and polyrotaxane (B) having at least two cyclic molecules and a linear-chain molecule passing through an opening of the cyclic molecules wherein the linear-chain molecule has blocking groups at both ends thereof, and   wherein the adhesive polymer (A) and the cyclic molecule of polyrotaxane (B) are bonded to form a crosslinked structure.   
     
     
         2 . The adhesive sheet for wafer processing as set forth in  claim 1 , wherein said adhesive polymer (A) has reactive functional group, said cyclic molecule has a reactive functional group, and the reactive functional group of said adhesive polymer (A) and the reactive functional group of said cyclic molecule forms a crosslinked structure by binding directly or indirectly. 
     
     
         3 . The adhesive sheet for wafer processing as set forth in  claim 1 , wherein storage elasticity at 25° C. of said adhesive layer is 2.5 MPa or less. 
     
     
         4 . The adhesive sheet for wafer processing as set forth in  claim 1 , wherein an adhesive force when releasing from a silicon wafer mirror face while the sheet being cut into a size having a width of 25 mm is 5000 mN/25 mm or less. 
     
     
         5 . The adhesive sheet for wafer processing as set forth in  claim 2 , wherein each of the reactive functional group of said adhesive polymer (A) and polyrotaxane (B) forms the crosslinked structure by binding via a crosslinking agent (C) comprising a crosslinking group capable of reacting with the reactive functional group of said adhesive polymer (A) and with the reactive functional group of said polyrotaxane (B). 
     
     
         6 . The adhesive sheet for wafer processing as set forth in  claim 5 , wherein the reactive functional group of said adhesive polymer (A) and the reactive functional group of polyrotaxane are the same functional group, and
 when the number of the reactive functional group comprised in the adhesive polymer (A) is taken as 1, a relative ratio α of the number of the reactive functional group comprised in polyrotaxane (B) to the number of the reactive functional group comprised in the adhesive polymer (A) is taken as α, and a relative ratio β of the number of the crosslinking group comprised in the crosslinking agent (C) to the number of the reactive functional group comprised in the adhesive polymer (A) is taken as β, then the adhesive layer satisfies a relation of 1+α−β≦ 1 . 2 .   
     
     
         7 . The adhesive sheet for wafer processing as set forth in  claim 5 , wherein the reactive functional group of said adhesive polymer (A) and polyrotaxane (B) are hydroxyl group, and the crosslinking group of said crosslinking agent (C) is isocyanate group. 
     
     
         8 . The adhesive sheet for wafer processing as set forth in  claim 1 , wherein a breaking elongation is 100% or more when a thickness of said adhesive layer is 1 mm. 
     
     
         9 . The adhesive sheet for wafer processing as set forth in  claim 1 , wherein a gel fraction of said adhesive layer is 90% or more. 
     
     
         10 . A method for processing a semiconductor wafer comprising:
 adhering a circuit surface of the semiconductor wafer formed with a circuit on a surface to the adhesive layer of the adhesive sheet for wafer processing as set forth in  claim 1 , and   backside processing of the semiconductor wafer.   
     
     
         11 . The method for processing the semiconductor wafer as set forth in  claim 10  wherein the backside processing of said semiconductor wafer is a backside grinding. 
     
     
         12 . A method for processing a semiconductor wafer comprising:
 adhering the semiconductor wafer formed with the circuit on a surface to the adhesive layer of the adhesive sheet for wafer processing as set forth in  claim 1 , and   dicing the semiconductor wafer.   
     
     
         13 . A production method of a semiconductor chip, comprising:
 forming a groove having a depth of cut shallower than a wafer thickness from a semiconductor wafer surface formed with a circuit with a bump,   adhering the adhesive sheet as set forth in  claim 1  to said circuit formed face,   thinning the wafer thickness by carrying out a backside grinding of said semiconductor wafer, and   dividing into each chip and picking up the chip.   
     
     
         14 . An adhesive sheet for semiconductor wafer processing comprising:
 a base film and an adhesive layer formed on one side thereof, wherein a thickness of the adhesive layer is 100 to 300 μm,   said adhesive layer is formed of a crosslinked structure by binding adhesive polymer (A) and polyrotaxane (B) via a crosslinking agent (C), said adhesive polymer (A) and polyrotaxane (B) has same reactive functional group, and   when the number of the reactive functional group comprised in the adhesive polymer (A) is taken as 1, a relative ratio α of the number of the reactive functional group comprised in polyrotaxane (B) to the number of the reactive functional group comprised in the adhesive polymer (A) is taken as α, and a relative ratio β of the number of the crosslinking group comprised in the crosslinking agent (C) to the number of the reactive functional group comprised in the adhesive polymer (A) is taken as β, then the adhesive layer satisfies a relation of 1+α−β≦ 0 . 8 ,   wherein adhesive polymer (A) comprises an adhesive polymer comprising a reactive functional group and   wherein polyrotaxane (B) comprises a polyrotaxane having at least two cyclic molecules and a linear-chain molecule passing through opening of the cyclic molecules wherein the linear-chain molecule has blocking groups at both ends thereof.   
     
     
         15 . The adhesive sheet for semiconductor wafer processing as set forth in  claim 14 , wherein a gel fraction of said adhesive layer is 40% or more. 
     
     
         16 . The adhesive sheet for semiconductor wafer processing as set forth in  claim 14 , wherein said adhesive layer has multilayered structure. 
     
     
         17 . The adhesive sheet for semiconductor wafer processing as set forth in  claim 14 , wherein said reactive functional group is hydroxyl group, and said crosslinking agent (C) is isocyanate based crosslinking agent. 
     
     
         18 . The adhesive sheet for semiconductor wafer processing as set forth in  claim 14  used for a grinding of a backside of the semiconductor wafer. 
     
     
         19 . The adhesive sheet for semiconductor wafer processing as set forth in  claim 18 , wherein a substance of said semiconductor wafer is provided with a projection having a height of 50 μm or higher on a surface. 
     
     
         20 . The production method of a thinned semiconductor wafer comprising:
 adhering the adhesive sheet for semiconductor wafer processing as set forth in  claim 14  to a projection face of the semiconductor wafer provided with projections on one side, and   grinding one face of the semiconductor wafer which is not adhered with said adhesive sheet for semiconductor wafer processing.   
     
     
         21 . The production method of the thinned semiconductor wafer as set forth in  claim 20 , wherein a height of said projection is 50 μm or more.